chore: update to tailwind v4

[Balastrong]

Tailwind v4 is out since a few months, let's keep it up to date.

As this touched a lot of files, here's some context of the major changes:

• All the changes in this PR are CSS/Tailwind classes only
• Tailwind config file is no longer required, the few extra configs are in app.css now
• Some classes have been renamed (automatically with npx @tailwindcss/upgrade), most notably gradient and screen
• bg-opacity-* utilities have been removed, bg opacity can be achieved with bg-gray-500/20
  • We have many dynamic colors from libraries that aren't picked up by tailwind, there's an expandable safelist in app.css
• Some spacings with space-y-* now behave slightly differently as they had performance issues in v3
  • The docs suggests to use gap instead
  • I replaced the broken spaces I found
• I deleted app.generated.css as that didn't seem to be used anywhere and wasn't touched since years

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Name	Link
🔨 Latest commit	5febfde

[KevinVandy]

fixed merge conflicts

[KevinVandy]

1 small issue with the filter by library styles not applying

[KevinVandy]

I couldn't find anything else wrong